Introduction Workers in aluminium production are exposed to a complex mixture of particles and gases potentially harmful to the airways, among them aluminium oxide (Al₂O₃). With the use of an exposure chamber, we aimed to examine the effects of short-term controlled exposure to Al₂O₃ on lung function and inflammatory markers in healthy volunteers.

Methods 15 men (age 19–31) were exposed in random order to clean air or Al₂O₃ particles (3.8–4.0 mg/m³) for 2 h including 30 min exercise (stationary bike, 75 W). The permissible exposure level (PEL) for Al₂O₃ by Occupational Safety and Health Administration, USA, is 5 mg/m³ time weighted average (TWA). Sham and particle exposures were separated by at least 2 weeks. Spirometry was carried out, and induced sputum and blood samples were collected 48 h before and 4 and 24 h after exposure.

Results Levels of sputum neutrophils (mean (±SEM)) was increased 24 h post-Al₂O₃ vs pre-Al₂O₃ exposure (43% (4) vs 31% (4), p=0.01) and the protein level of interleukin (IL)-8 had a 4.8 (0.9)-fold change increase 24 h after exposure (p<0.01). Following Al₂O₃ exposure, gene signatures in sputum were significantly increased related to several pathways.

Conclusions The present study suggests that controlled exposure to Al₂O₃ particles at levels below PEL (TWA) induces airway inflammation in healthy humans marked by elevated neutrophils and elevated IL-8. In addition, increased expression of genes associated with several biological processes was observed in sputum. Interestingly, inhaled Al₂O₃-induced effects were localised to the airways and not systemic.